Ligation is a medical procedure in which an elastic band, or ligating band, is placed about tissue to prevent fluid flow therethrough. Where a ligating band is placed about, for example, a ballooning varix, polyp, hemorrhoid, or pre-cancerous lesion, a contracted ligating band induces fusion and healing in the base tissue and subjects the ligated tissue to necrosis. The necrotic tissue eventually separates from the surrounding tissue and passes into the human system. Alternatively, ligation may also be used for purposes of sterilization, wherein a ligating band may be placed over a folded loop portion of a Fallopian tube or a vas deferens to prevent the passage of internal reproductive fluids.
Means for delivering ligating bands, or ligating band dispensers, take various forms. One such form is a dedicated ligating band dispenser instrument which has a dispensing portion at a distal end, an actuating mechanism at a proximal end, and a typically rigid shaft therebetween. These instruments are useful for ligating tissue in which the user has access to the tissue to be ligated, e.g., tissue exposed through an invasive surgical procedure.
In contrast, ligating band dispensers may be positioned on the distal tip of an endoscope or a laparoscope. An endoscope is a conventional medical device used for viewing, exploring, and delivering therapies to internal regions of a patient. A laparoscope is a specialized endoscope for viewing a patient's peritoneal cavity. Unlike dedicated ligating band dispensing instruments, an endoscope allows minimally invasive intrusion into a patient.
FIGS. 1 and 2 illustrate a conventional endoscope. Endoscope 10 has a control portion 12 and a insertion portion 14 terminating at insertion tip 16. Insertion portion 14 is of such a length to permit access to internal regions of a patient.
FIG. 2 illustrates the face of insertion tip 16. A number of channels extend from the control portion 12 to the insertion tip 16, where the channels terminate in functional outlets 18-26. For the purposes of this example, outlet 18 is a light source; outlet 20 is a wide-field image sensing device, which transmits a video or fiber optic signal to a coupled monitor or eyepiece (not shown) at control portion 12; outlet 22 delivers a stream of water or air for clearing the image receiving device or flushing an internal bodily region; and outlet 24 is an outlet to a working (or biopsy) channel. Inlet 28 of the working channel can be coupled to a suction device or a lavage fluid source (not shown) or can receive various medical instrumentation (not shown) for passage through the working channel and outlet 24. Optional outlet 26, for larger diameter endoscopes, is an outlet for a second working channel. A second working channel allows additional operations in a manner consistent with the working channel described above.
Endoscope ligating band dispensers are fixedly mounted about and protrude from insertion tip 16 of a hosting endoscope, wherein such dispensers carry one or more expanded ligating bands about their outer diameter. Projecting from insertion tip 16, conventional dispensers inherently narrow the field of view of the image sensing device of outlet 20. In an effort to improve such impairment, some conventional devices are fabricated from a transparent material. While such material may facilitate the outward passage of light from outlet 18, such material does not practically improve the field of view for the wide-field image sensing device. Specifically, the use of transparent material commonly induces distortion about the periphery of a displayed image. Distortion is a product of both the curvature of the dispenser and the accumulation of bodily fluids about the outer surface of the dispenser. Ligating bands stored on the outer diameter of these dispensers further obstruct the field of view through the dispenser material.
A conventional endoscope ligating band dispenser is shown in FIG. 3. Dispenser 1000 is capable of dispensing multiple ligating bands 1002, whether individually or sequentially. Typical of the prior art, dispenser 1000 is cylindrical and hollow in nature, where an inner periphery of dispenser 1000 defines a cavity and an outer periphery carries the ligating bands 1002. Dispenser 1000 projects from the distal end of insertion tip 16. Accordingly, dispenser 1000 inhibits the field of view of a wide-field image sensing device (not shown) of the hosting endoscope in accordance with the limitations of conventional devices outlined above.
Conventional dispensers, such as dispenser 1000, increase the length of insertion tip 16. A ligating band dispenser-equipped endoscope is commonly used within a hollow body cavity, for example, an esophagus. Insertion tip 16 must assume almost a 90.degree. bend with respect to the longitudinal axis of the insertion portion 14 to obtain a clear view normal to the inner surface of an esophagus. The additional length of the ligating band dispenser from insertion tip 16 can significantly restrict the motion and flexibility of insertion tip 16 within a hollow body cavity. Accordingly, the added length, coupled with the severely restricted peripheral view, makes the presence of conventional ligating band dispensers an operational liability during the exploration and placement phases of ligation procedures.